1. Field of the Invention
The present invention relates to an illumination apparatus in which usage efficiency of light is high and variations in quantity of light are little, and to a display apparatus which projects and displays an image by using the illumination apparatus.
2. Description of the Related Art
Conventionally, as a high directivity illumination apparatus used for a projection display apparatus or the like, examples in which an LED emitting diffused light and a tapered rod are provided thereat are disclosed in U.S. Pat. Nos. 6,318,863 and 6,227,669 B1. Namely, an LED light source is disposed so as to be close to a small-diameter opening of the tapered rod. Light which is incident from the small-diameter opening of the tapered rod into the tapered rod is transmitted so as to be totally reflected at the internal surface of the tapered rod. The respective light rays are converted so as to have small angles, and are emitted from a large-diameter opening of the tapered rod toward a projection lens. Accordingly, an illumination apparatus which can be used for a projection display apparatus using an image display member in which an allowable angle of incident light is narrow can be obtained.
Incidentally, a method for holding an optical part which has a rod shape is disclosed in Japanese Patent Application KOKAI Publication (JP-A) No. 8-227034 and JP-A No. 10-253923. The object of the method in 8-227034 is ensuring a positioning accuracy over a long period, and radiating a thermal stress. In order to attain the objects, a structure in which a rod integrator side surface is biased by a supporting member having a mask function as well and springs is disclosed. Further, the object of 10-253923 is in ensuring a heat resistance of the supporting member of the rod integrator whose temperature becomes high, and ensuring a structural holding accuracy. In order to attain the objects, a structure is disclosed in which the rod integrator is biased onto a supporting member formed from a metal plate by using spring members from the side surface, and at the same time, the rod integrator is biased in the optical axis direction due to the spring members being hooked on one portion of an incident end plane.